Award Partial Credit

Tags: educator how-to

You can configure a multi-select problem to award partial credit to learners who submit an answer that is partly correct.

For an overview of partial credit in problems, see Awarding Partial Credit for a Problem.

In the following example, the learner selected two of the three correct choices, and did not select any incorrect choices. The learner therefore had four out of five correct answers. Because the course team set this problem up to award partial credit for every correct answer selected and every incorrect answer left unselected (known as Using the Every Decision Counts Method), the learner earned 80% of the points for this problem.

You can use the following methods to award partial credit in a multi-select problem.

Using the Every Decision Counts Method

You can configure a multi-select problem so that every selection a learner makes for the multi-select problem is evaluated and scored. This method is known as every decision counts (EDC).

With EDC, if “n” is the number of possible answers, learners earn 1/n of the total possible score for each correct answer they select. Learners receive partial credit for every correct answer selected and every incorrect answer left unselected.

For example, if there are four answers, every answer that a learner matches is worth 25% of the total score. A learner also gains 25% for each incorrect answer that a learner does NOT select.

The following table shows how the different combinations of learner selections would score for one EDC problem whose answers are as follows.

• Correct answers: A, B, D

• Incorrect answers: C

Learner’s Selections	Score	Explanation
A, B, D	100%	The learner matched each of the 3 correct answers for 75%, and also gained 25% for not selecting the incorrect answer.
A, B	75%	The learner matched 2 of the correct answers for 50%, and also gained 25% for not selecting the incorrect answer.
A, B, C	50%	The learner matched 2 of the correct answers for 50%, but selected the incorrect answer.
A, C	25%	The learner matched 1 of the correct answers for 25%, but selected the incorrect answer.

Configure an EDC Multi-select Problem

To configure an EDC multi-select problem, you add the partial_credit="EDC" attribute to the <choiceresponse> element in the problem OLX.

For example, the following OLX shows the multi-select problem template after it is updated to provide partial credit.

<problem>
  <choiceresponse partial_credit="EDC">
    <label>Which of the following is a fruit?</label>
    <description>Select all that apply.</description>
    <checkboxgroup>
      <choice correct="true">apple</choice>
      <choice correct="true">pumpkin</choice>
      <choice correct="false">potato</choice>
      <choice correct="true">tomato</choice>
    </checkboxgroup>
  </choiceresponse>
</problem>

Using the By Halves Method

You can configure a multi-select problem so that for every answer that a learner gets wrong, either by not selecting a correct answer or by selecting an incorrect answer, half of the remaining points are deducted from the learner’s score. This method is known as scoring by halves.

Note

By design, partial credit by halves requires the number of answer options to be more than twice the number of incorrect answers. In addition, partial credit is not given for more than two wrong answers, regardless of the total number of answer options. In other words, two wrong answers is scored at 25% only if there are at least 5 answer options. Three or more wrong answers is always scored at 0%, regardless of the number of total answer options.

Partial credit using the by halves method is calculated as follows.

• If a learner makes no errors, she receives full credit for the problem.

• If a learner makes one error, she receives 50% of the possible points, as long as there are three or more choices in the problem. If a learner makes one error and there are only two choices in the problem, no credit is given.

• If a learner makes two errors, she receives 25% of the possible points, as long as there are five or more choices in the problem. If a learner makes two errors and there are only three choices or four choices in the problem, no credit is given.

• If a learner makes three errors, she receives no credit for the problem, regardless of how many answer options there are.

The following tables illustrate partial credit score using the halves method, for problems with an increasing number of total answer options.

Number of Incorrect Answers	Number of Answer Options	Credit Given (%)
0	2	100
1	2	0
2	2	0

Number of Incorrect Answers	Number of Answer Options	Credit Given (%)
0	3	100
1	3	0
2	3	0
3	3	0

Number of Incorrect Answers	Number of Answer Options	Credit Given (%)
0	4	100
1	4	50
2	4	0
3	4	0
4	4	0

Number of Incorrect Answers	Number of Answer Options	Credit Given (%)
0	5	100
1	5	50
2	5	25
3	5	0
4	5	0
5	5	0

Number of Incorrect Answers	Number of Answer Options	Credit Given (%)
0	7	100
1	7	50
2	7	25
3	7	0
4	7	0
5	7	0

Configure a By Halves Multi-select Problem

To configure a by halves multi-select problem, you add the partial_credit="halves" attribute to the <choiceresponse> element in the problem OLX.

The following example shows a multi-select problem that provides partial credit by halves.

<problem>
  <choiceresponse partial_credit="halves">
    <label>Which of the following is a fruit?</label>
    <description>Select all that apply.</description>
    <checkboxgroup>
      <choice correct="true">apple</choice>
      <choice correct="true">pumpkin</choice>
      <choice correct="false">potato</choice>
      <choice correct="true">tomato</choice>
    </checkboxgroup>
  </choiceresponse>
</problem>

See also

About Multi-select Problem (reference)

Add a Multi-select (Checkbox) Problem (how-to)

Adding Feedback and Hints to a Problem (how-to)

Multi-select Problem OLX Reference (reference)

Maintenance chart

Review Date	Working Group Reviewer	Release	Test situation

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